Insulator for electric fences and the like



2 Sheets-Sheet 1 N 2 4/ 2 m l M .M 3 1 v I m B 1 '0 RV ATTORNEY Oct. 20, 1970 R. M. WILSON INSULATOR FOR'ELECTRIC FENCES AND THE LIKE Filed July 7, 1969 Oct. 20, 1970- I M, w so 3,535,432

INSULATOR FOR ELECTRIC FENCES AND THE LIKE Filed July v, 1969 2 Sheets-Sheet 2 a /6 j 35 5 5 w 225 30 7 E4 5 /4 a E;

IIIIIIIII IIIIIHWIH YINVENTOR ROBERT M. WILSON 1 'ATTO RN E Y United States Patent O 3,535,432 INSULATOR FOR ELECTRIC FENCES AND THE LIKE Robert M. Wilson, Battle Creek, Mich, assignor to Dare Products, Incorporated, Battle Creek, Mich., a corporation of Michigan Filed July 7, 1969, Ser. No. 839,225 Int. Cl. H01b 17/16 US. Cl. 174-175 12 Claims ABSTRACT OF THE DISCLOSURE An insulator with a spool-like body having radial end flanges and a pair of finger-like projections extending from the latter toward the medial part of the body, such fingers being substantially parallel to each other and to the body and spaced apart from each other and from the body, and said fingers each having a pair of spaced ear portions on its underside which extend toward the body and which define a notch between them for retaining a wire within the notches and between the fingers and the body of the insulator.

BACKGROUND OF THE INVENTION Numerous different types of insulators have heretofore been developed, and many actually used, for mounting electric fence wires on fence posts while simunltaneously insulating the wire from the post. Even in early electrified fence systems, a significant measure of such insulation was necessary, since the fences are fully exposed to the elements and in the presence of rain or heavy moisture resulting from such exposure the electrified wires would become shorted directly to ground, by low-resistance leakage paths extending over the surface of the insulators and down the surface of the fence posts (which may be of wood or of metal).

Such short-circuiting has always been a problem in electrified fencing, and the search for improved insulators has been a continuous one extending over many years. Efforts to provide improved insulators have centered primarily upon electrical characteristics, i.e., resistance to shorting, both by reason of dielectric breakdown of the body of the insulator and also as a result of arcing along lowresistance paths over the body of the insulator under conditions of heavy moisture or dust. Improvements of this nature have become increasingly necessary as the energizing sources have been improved over the years, and this is particularly so in recent times, when the development of high-capacity solid state semi-conductors has brought about small and compact sources of excitation which can produce 5,000 volts of shocking power, normally in the form of short-duration pulses. While such high voltages are quite clearly desirable in terms of effect upon fenced-in livestock, they also quite clearly pose a definite handling problem, since they are capable of arcing over a greatly increased air gap and through higher resistivity than earlier low-voltage systems.

While the aforementioned continuing search for improved insulators has centered upon the problem of insulation and arc elimination for ever-increasing voltage levels, it has also focused upon the need for electrically effective insulators having structures for directly mounting the current-carrying wire, so that auxiliary or additional fastening or mounting members and the like are not re quired. This aspect is not totally separate from the insulating and arc-eliminating properties of the insulator, however, since the means for attaching the wire to the insulator can frequently be the very instrumentality by which the insulator becomes short-circuited in use. Furthermore, movement of the wire with respect to and "ice against the insulator, as for example under the influence of windstorms, animals pushing against the fence, and the like, must definitely be avoided, particularly in the case of integrally molded insulators, since the insulators can rapidly be worn away by this influence and experience early electrical failure as a result.

SUMMARY OF THE INVENTION It is a major objective of the present invention to provide an improved form of insulator for electric fences and the like, in which insulating effectiveness and arc elimination are extremely high, in which a novel unitary quick-connect means for the wire is provided, and in which novel attachment structures are provided adding structural strength and rigidity to the insulator and helping to prevent early structural failure after installation. Some of the major advantages provided by the invention are, therefore, an insulator which will withstand extremely high energizing voltages in actual usage without allowing shorting, whether by dielectric breakdown or by arcing, together with providing an insulator with an integral wireattachment means that quickly and securely retains the fence wire in the desired position, and an insulator having improved structural strength during usage and providing for long operating life.

Briefly stated, the invention comprises an electrical insulator having a spool-like body and a pair of mutually spaced and generally parallel projections carried by the body and extending from opposite directions over medial portions thereof, with each projection having an underside which is spaced laterally from the axis of the body and from the outer surface thereof and having at least one ear portion extending toward the body, such that a notch is defined in the underside of each projection forming a pair of spaced wire-retention means positioned on either side of the body and cooperating therewith to entrap a wire in a secure and dependable manner.

IN THE DRAWINGS FIG. 1 is a fragmentary perspective view of the insulator attached to a typical fence post and mounting a fence wire.

FIG. 2 is an enlarged, overhead plan view of the components shown in FIG. 1 as viewed from the plane 11-11 of FIG. 3, looking in the direction of the arrow.

FIG. 3 is a further enlarged, side elevational view of the structures seen in FIGS. 1 and 2.

FIG. 4 is a sectional end elevation taken through the vertical plane IVIV of FIG. 2.

FIG. 5 is a sectional plan view taken through the plane VV of FIG. 3.

FIG. 6 is a sectional end elevation taken through the plane VIVI of FIG. 3; and

FIG. 7 is a sectional end elevation taken through the plane VII-VII of FIG. 3.

PREFERRED EMBODIMENT Referring now in more detail to the drawings, the insulator 10 of the invention is seen in FIG. I mounted to a typical fence post 12, shown for purposes of illustration as an elongated, generally cylindrical rod. Basically, the insulator 10 is an integrally molded structure, preferably of a generally rigid polymeric material such as linear polyethylene, and of the general type characterized as having a spool-like form. That is, it includes a barrel or body 14 extending between a pair of larger-diameter for receiving a wingnut 22 or the like, whereby the insulator is mounted to the fence post 12 by forcing it compressively against the post.

The barrel or body 14 of the insulator is basically semicylindrical, but preferably includes a thickened or built-up portion 15 on the side thereof which is positioned upwardly during actual usage (FIGS. 3, 6 and 7). As illustrated, the uppermost extremity of portion 15 may form a rectangular ridge which is narrower than the body itself and which extends longitudinally thereof. This ridge forms a horizontal support table for the wire 24 (FIG. 2) which is to be mounted by the insulator 10'. In this respect, it .is to be noted that although the insulator assembly of the invention may be relatively small in overall size, on the order of one inch in length, it will vertically mount a stranded conductor having more than a single wire. Also, the thickened nature of the wiresupporting bridge portion 15 is significant, since it provides increased dielectric between the current-carrying wire mounted by the insulator and the J-hook which secures the insulator to the fence post, for increased resistance against shorting of the wire through the J-hook to the post, together with increased wear resistance against the abrasive effects of even minor movements of the wire with respect to the insulator during use.

As may be observed from the drawings, the end flanges 16 and 18 of the insulator are preferably very wide in diameter; in fact, the diameter of the flanges may be on the order of twice the length of the body interconnecting the flanges and on the order of four times larger than the nominal diameter of the body 14 (FIG. 5). This relationship provides an extremely high effective resistance to arcing and shorting of current from the wire 24 over the flanges 16 or 18 to the J-hook 20 or the fence post 12, and will very satisfactorily accommodate the conditions of elevated operating voltage levels currently produced by modern energizing sources for the wire 24. In this connection, it will be noted that the flanges 16 and 18, although wide in diameter, may be quite thin, having a thickness which is only on the order of about one-seventh that of the body 14.

Extending inwardly toward the medial area of the body 14 from each of the end flanges 16, 18 is a fingerlike projection 26, 28, respectively, each of which may be integrally molded with its respective end flange and with the body 14. Each of the projections 26, 28 extends toward the oppositely-disposed end flange, but terminates short of the same, to allow a clearance therebetween for the wire 24 when the latter is mounted; that is, the wire 24 is mounted while in a slack condition, and it is lightly and elastically deformed into an S-shaped pattern for downward insertion between the respective ends of the projections 26 and 28 and the end flanges 18 and 16.

The end extremity of each of the projections 26, 28 has a downwardly-depending ear onits underside, designated 126, 128, respectively. Also, each of the projections has a downwardly-depending ear 226, 228 at the end thereof where it joins its respective end flange. As illustrated (FIG. 3), each of the ears on the finger projections are all uniformly rounded at their corners to guard against moisture retention and droplet adherence, which can be an important cause of shorts resulting from arcing across the surface of the body under rainy or other wet environmental conditions. The cars on each finger are formed in a spaced-apart configuration to define a notch therebetween, and the Wire 24 is disposed within these notches when in its mounted position (FIGS. 2, 3 and 5). The notches so formed thus provide a very effective entrapment means with the upper surface of the body portion 15 for securely holding the wire to be mounted, since once the wire is placed into position and then tightened to the extent desired, it is restrained against movement in all radial directions, against the influences of Wind, livestock, and the like. That is, each of the downwardly-depending ears on each of the finger projections restrains the wire from being moved in either lateral direction, while the fingers themselves restrain the wire vertically, thus effectively staking the wire into place and holding it there at a pair of points spaced on either side of the body while the latter restrains the wire and supports it against downward movement. Under these circumstances, although the wire is free for purposes of longitudinal movement, as to allow proper tensioning thereof during installation or subsequent maintenance and to provide a desired degree of yield in the event a heavy animal pushes against the wire between posts, all other directions of possible movement are very effectively reduced to the point of substantial elimination, thereby significantly reducing the wear which the wire can exert on the surfaces of the insulator when rubbed against the same.

It will be observed that the insulator 10 preferably has an axially-extending hub portion 30 outwardly of end flange 16, providing a load-bearing member for the wingnut 22 when tightened. Also, the insulator has a largediameter, generally annular hub portion 32 at its opposite end extremity, adjacent the post 12. More particularly, the hub portion 32 includes an annular shoulder 34 surrounding a generally tubular skirt 36 (FIGS. 2, 3, 4 and 5). This design allows for the use of a sharply-toothedmetal or other crown such as is disclosed in the inventors earlier U.S. Pat. No. 3,098,117 where this is made desirable by circumstances and the type of post and insulator used. However, skirt 36 preferably has a series of four indentations or recesses 38 arranged in quadrature with respect to each other about the circumference of the skirt. As may be seen in FIGS. 3 and 5, a pair of oppositelydisposed recesses 38 will fit against a post such as the one indicated at 12 to index the insulator with respect to the post during the mounting of the insulator thereon. As will be appreciated, this configuration adds a significant degree of stability for the insulator after it is mounted.

When the insulator is mounted to the post 12 and the wingnut 22 tightened to hold the insulator in place, the insulator is placed under axial compressive loading between the wingnut and the post. It has become a known characteristic of integrally molded insulators made from synthetic plastic materials to fail under such compressive loading at a relatively early date, normally by axial collapse or bending of the body portion. The present invention provides a novel and highly effective solution to this problem, by the presence of a pair of spaced reinforcement ribs 40, 42 (FIGS. 4 and 5) located inside the skirt 36 and extending chord-like across oppositely-disposed sections of the skirt. The presence of such reinforcing ribs significantly increases the strength of the insulator construction, and has been found to materially resist the bending and collapse which has characterized other devices. The location and nature of the ribs 40, 42 allows for their formation as integral elements in the molding of the insulator, which can be manufactured in a single molding operation.

It is entirely conceivable that those skilled in the art may well devise certain variations and modifications of the preferred embodiments disclosed and described hereinabove. Consequently, the specific structures which are illustrated and described should be regarded as being for purposes of illustration, and not as determinative of the only practical or desirable way of implementing the concept on which the invention is based.

I therefore particularly point out and distinctly claim as my invention:

1. In an electrical insulator for use in mounting a current-carrying wire upon a post or like support while insulating the wire from the latter, and characterized by a barrel-like body attachable to such post to support the wire, the improvement comprising: a paif of mutually spaced apart and generally parallel projections carried by said body and extending from opposite directions over medial portions of the body; each of said projections having an underside which is spaced laterally from the axis of the body and from the outer surface thereof; each of said projections having at least one ear portion along its said underside defining at least in part a recess formed therein for entrapping said wire at spaced points on either side of the axis of the body, wherein said recesses are arranged in mutual alignment on a straight-line locus disposed substantially perpendicular to a line therethrough parallel to the axis of said barrel-like body.

2. The improvement in an insulator defined in claim 1, wherein said projections and said body are integral with each other.

3. The improvement in an insulator defined in claim 1, wherein each of said projections has a pair of said ear portions along its underside, said ear portions in each pair being spaced apart to define side edges of said recesses.

4. The improvement in an insulator defined in claim 1, wherein said body comprises a spool having a pair of axially spaced radially-extending flanges, and each of said projections is carried on a different one of said flanges and extends toward the other.

5. The improvement in an insulator defined in claim 4, wherein both of said projections are substantially wholly within the peripheral silhouette of said flanges.

6. The improvement in an insulator defined in claim 4, wherein said body, said flanges, and said projections are all integral with each other.

7. An electrical insulator for use in attaching a wire to a post or the like, comprising, in combination: a body having a central barrel portion; and a pair of generally parallel arm members supported on said body and extending from opposite directions toward and over said central barrel portion; each of said arm members having a generally C-shaped underside portion defining a recess located adjacent the outer surface of said body, for en trapping a wire within the recess, between said underside portion and said barrel portion, wherein said recesses are arranged in mutual alignment on a straight-line locus substantially perpendicular to a line therethrough parallel to the axis of said barrel portion.

8. The electrical insulator of claim 7, wherein said rerecess in the underside of said arm members is of such size as to extend around a major part of the circumference of such wire.

9. In an electrical insulator, of the type having a spoollike body with an axial opening for a mounting member which exerts an axially compressive loading force on the body in attaching the same endwise to a post or the like, the improvement comprising: a hub portion on the end of said body nearest said post; said hub portion comprising outwardly-protruding skirt portions extending endwise of said body; and at least one reinforcing rib element extending transversely of said body axis and interconnecting oppositely-disposed spaced points on said skirt portions, for strengthening the skirt and body against collapse under said loading forces.

10. The improvement in electrical insulators defined in claim 9, including at least two of said reinforcing rib elements, each disposed on an opposite side of said axial opening.

11. The improvement in electrical insulators defined in claim 9, wherein said rib element and said skirt portions are integral with each other.

12. The improvement in electrical insulators defined in claim 11, wherein said integral rib element and skirt portions are also integral with said body.

References Cited UNITED STATES PATENTS 927,321 7/1909 Bond 174-175 X 2,829,192 4/1958 Nield 174-158.2 X 2,870,245 1/1959 Malme 174158.2 X 3,071,640 1/1963 Langlie et a1. 174-l58.2 3,098,117 7/1963 Wilson 174-1632 X FOREIGN PATENTS 1,277,339 10/1961 France.

LARAMIE E. ASKIN, Primary Examiner I US. Cl. X.R. 1741 63 

